1. Field of the Invention
The present invention relates to an antenna module installed in a wireless communication terminal. More particularly, the invention relates to a built-in antenna module for a wireless communication terminal in which a Bluetooth module is integrated into a structure with an antenna for base station which communicates in a different frequency band from the Bluetooth module, thereby efficiently utilizing a limited space in a miniaturized terminal.
2. Description of the Related Art
In general, a wireless communication terminal refers to a portable communication device capable of transmitting and receiving voices, texts and image data through wireless communication. The examples include a personal communication service (PCS) terminal, a Personal Digital Assistant (PDA), a smart phone, a next-generation mobile communication (IMT-2000) terminal, a wireless Local Area Network (LAN) terminal and the like.
The wireless communication terminal adopts a helical antenna or a dipole antenna to enhance its transmission and reception sensitivity. These are external antennas, which thus are extended out of the wireless terminal.
The external antennas have an advantage of non-directional radiation characteristics. But as they are extended to the outside, they are much likely to be damaged by external force, inconvenient for carrying around, and may be a hindrance to attractive exterior design of the terminal.
To overcome such a problem, planar built-in antennas such as a micro-strip patch antenna or Planar Inverted-F Antenna are adopted in the wireless communication terminal recently since they can be installed in the terminal without being extended outward.
In addition, Bluetooth communication technology is adopted for the terminal to enable sending and receiving wireless data at a transmission rate of 1 M/bit in a short range of about 10 M in a 2.4 Ghz band. In order to conduct the short-range communication using the Bluetooth communication technology, a Bluetooth module needs to be included in a main board of the terminal.
The Bluetooth module is composed of a frequency converter for converting a wire signal to a wireless signal, an amplifier and a Bluetooth antenna.
FIG. 1 is an exploded view illustrating the built-in antenna and the Bluetooth module provided on a board of a terminal according to the prior art. As shown, an antenna module 2 is hooked detachably onto a board 1 of a terminal body (not shown), and a Bluetooth module 10 is mounted on the board 1.
The antenna module 2 includes a pad 3 having a plurality of fastening legs 3a corresponding to fastening grooves 1a formed on the board 1, a conductor 4 shaped like a metal plate formed on an upper surface of the pad 3, and a feeder 5 extended from the conductor 4 to be inserted into a contact hole 1b. 
In addition, the Bluetooth module 10 is provided on the board 1 to communicate with electronic devices in a different frequency band from that of the antenna module 2 communicating with the base station. The Bluetooth module 10 includes components such as a wireless circuit, a baseband signal processor, a central processor, an SRAM and a flash device mounted on a module board 11. These components are protected by a shield cover 18, and a Bluetooth antenna 12 is provided at a side of the module board 11 via an input/output electrode 13.
Such a Bluetooth module 10 can be made smaller in accordance with the miniaturization of the terminal by decreasing the number and size of the components contained therein. However, as an additional space is needed for mounting the Bluetooth module 10, there is a limitation in reducing the volume of the terminal when the antenna module 2 and the Bluetooth module 10 are provided on the same plane.
In addition, the Bluetooth module 10 is typically mounted near a lower part of the board 1. This mounting position of the Bluetooth module 10 corresponds to the portion of the terminal held by the hand of the user, which interferes with the RF characteristics of the Bluetooth antenna, thereby degrading the reliability of the terminal.
Therefore, although providing the antenna module 2 and the Bluetooth module 10 together in the terminal body allows an attractive exterior of the terminal and increases portability, there is a limitation in miniaturizing the terminal and in attaining highly sensitive RF capabilities of the antenna.